Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, a generator, a gearbox, a nacelle, and a rotor having a rotatable hub with one or more rotor blades. The rotor blades capture kinetic energy of wind using known airfoil principles. More specifically, the rotor blades typically have the cross-sectional profile of an airfoil such that, during operation, air flows over the blade producing a pressure difference between the sides. Consequently, a lift force, which is directed from a pressure side towards a suction side, acts on the blade. The lift force generates torque on the main rotor shaft, which is geared to a generator for producing electricity. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.
The rotor blades generally include a suction side shell and a pressure side shell typically formed using molding processes that are bonded together at bond lines along the leading and trailing edges of the blade. Further, the pressure and suction shells are relatively lightweight and have structural properties (e.g., stiffness, buckling resistance and strength) which are not configured to withstand the bending moments and other loads exerted on the rotor blade during operation. Thus, to increase the stiffness, buckling resistance and strength of the rotor blade, the body shell is typically reinforced using one or more structural components (e.g. opposing spar caps with a shear web configured therebetween) that engage the inner pressure and suction side surfaces of the shell halves. The shell of the rotor blade is generally built around the spar caps of the blade by stacking layers of fiber fabrics in a shell mold. The layers are then typically infused together, e.g. with a thermoset resin.
It is also known in the art to change the aerodynamic characteristics of the rotor blades by adding aerodynamic add-on features, including but not limited to vortex generators, chord extensions, fairings, low noise trailing edge serrations, leading edge extensions, trailing edge extensions, spoilers, gurney flaps, stakes, protrusions, and/or other structures on the surface of the blade. Conventional rotor blade add-ons are typically bonded to the blade shell by applying a bonding agent or adhesive to the shell, positioning the blade add-on atop the adhesive, and allowing the adhesive to cure. Such bonding agents, however, can be expensive and time-consuming to apply.
Thus, the art is continuously seeking new and improved airflow modifying elements or add-on features for rotor blades and related assembly methods that address the aforementioned issues. More specifically, the present disclosure is directed to thermoplastic airflow modifying elements for wind turbine rotor blades that can be welded to the surface of the blade and therefore do not require an additional bonding agent.